14.Extremophiles(极端微生物) are organisms that have been discovered on earth that survive in environments that were once thought not to be able to sustain life.These extreme environments include intense heat,highly acidic environments,extreme pressure and extreme cold.Different organisms have developed varying ways of adapting to these environments,but most scientists agree that it is unlikely that life on Earth originated under such extremes.
Adapting to Extreme Heat
In the 1960s,heat resistant bacteria were discovered in hot springs in Yellowstone National Park.This bacteria,thermus aquaticus thrives at temperatures of 70°C but can survive temperatures of 50°C to 80°C.A few years after these were discovered,other bacteria were found living under even more extreme conditions.Hydrothermal vents (热水流火山口) were discovered deep in the ocean and under such high pressure that the water boils at 340°C.It was a surprise to researchers to discover bacteria living and thriving in the vents at such extreme temperatures and pressures.Not only were there bacteria,but centimeters away where the water was cooler,was a complete ecosystem living off the bacteria.There were clams and tubeworms among other species.
Adapting to Extreme Cold
Other extremophiles have developed ways to cope with cold.Deep ocean water is as a fairly constant temperature of 2°C,but because of its salt content,in colder areas,ocean water can reach temperatures as low at-12°C without freezing.Extremophiles known as psychrophiles(低温微生物) are known to survive at these low temperatures.Different species have come up with different ways to survive these cold temperatures.Some have developed substances,such as glycerol(甘油) or antifreeze proteins which lower the freezing point of water by several degrees.
The main danger to organisms of freezing is the damage caused by ice crystals as water freezes and expands.Some species of frogs and turtles have proteins which actually facilitate the freezing of body liquids.If the animal's body liquids begin to freeze,a chain reaction is started and all of the body's liquids freeze rapidly.This prevents the formation of ice crystals large enough to do any damage.Many kinds of microorganisms can survive freezing and thawing,as long as the problem of ice crystals is avoided.
66.An"ecosystem"(paragraph 2)can be best described asA.
A.an interacting community that contains both living and non-living organisms
B.a large collective term for animals that eat bacteria
C.different types of plants and animals that cooperate for food
D.the place where temperatures and conditions are dangerous and extreme
67.The formation of large ice crystal is dangerous mostly becauseC.
A.the animal can no longer breathe,and nutrient can't be carried around the body
B.proteins cause the animal's body liquids to freeze
C.the freezing and expansion of water could damage the animal's organs
D.the temperature inside the animal becomes too cold to survive in
68.Which of the following statements is FALSE according to the passage?D
A.Extremophiles live in environments other organisms cannot survive in.
B.Extremophiles can survive in both acidic and high pressure environments.
C.The thermophile lives in extremely high temperatures.
D.Fresh water has a constant temperature of around 2° C.
69.The purpose of this article is toC.
A.amuse and entertain scientists
B.provide a personal opinion about an issue
C.educate and inform readers
D.predict the beginning of evolution.
分析 本文属于说明文阅读,作者通过这篇文章主要向我们讲述了地球上已经发现了一些极端微生物,它们可以适应高温、高酸、高压或者极端寒冷的环境,不同的生物有不同的发展适应这些环境的方法.
解答 66.A.推理判断题.根据文章第二段"Not only were there bacteria,but centimeters away where the water was cooler,was a complete ecosystem living off the bacteria"不仅有细菌,几厘米远的地方还有低温的水,是一个完整的生态系统;可知完整的生态系统是一个包括生物和非生物的有趣社区;故选A,
67.C.细节理解题.根据文章最后一段"The main danger to organisms of freezing is the damage caused by ice crystals as water freezes and expands"对生物体的主要危险是冻结的冰晶和水结冰膨胀造成的损害;即生物体器官的损伤;故选C.
68.D.细节理解题.根据文章第三段"Deep ocean water is as a fairly constant temperature of 2°C"海洋深层水拥有相当恒定的温度2°C,可知淡水的恒定稳定2°C是错误的;故选D.
69.C.主旨大意题.通读全文可知,文章主要讲地球上已经发现了一些极端微生物,并举了例子,作者只是描述了已有事实,并没有发表自己的意见,由此可见作者的目的旨在教育和告知读者这些信息.故选C.
点评 考察学生的细节理解和推理判断能力,做细节理解题时一定要找到文章中的原句,和题干进行比较,再做出正确的选择.在做推理判断题不要以个人的主观想象代替文章的事实,要根据文章事实进行合乎逻辑的推理判断.